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In this investigation, an automotive component made of nylon as a structural element was studied by several characterization techniques to identify material properties. Firstly, a Fourier transform infrared spectroscopy (FTIR) was carried out to obtain information about composition, then, differential scanning calorimetry (DSC) was used to extract useful information on sample thermal behavior. The humidity and volatile materials percentage could be assessed by thermogravimetry analysis (TGA). Morphology and topography were carried out by optical microscopy, moreover, X-ray Tomography allows it to display the sample’s inner part. Characterization shows that the component could have been contaminated or exposed to conditions that promote degradation after the manufacturing process. Finally, computerized X-ray tomography displayed that both samples showed a difference in porosity in a fractured sample and a healthy sample. All the above implies a change in the mechanical integrity of the fractured material but might not omit the fact that it could have been subjected to any type of impact or mechanical effort.

Funding Information: This work was financed by national funds from FCT—Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication—i3N. Furthermore, the work received funding from FCT in the scope of projects UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences—UCIBIO and the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy—i4HB. This work also received funding from the European Community’s H2020 program under grant agreements 716510 (ERC-2016-StG TREND), 787410 (ERC-2019-AdG DIGISMART) and 952169 (SYNERGY, H2020-WIDESPREAD-2020-5, CSA), 101008701 (EMERGE, H2020-INFRAIA-2018-2020). B. J. Coelho acknowledges FCT for the attribution of grant SFRH/BD/132904/2017 and grant COVID/BD/152453/2022. Publisher Copyright: © 2023 by the authors. Poly(p-xylylene) derivatives, widely known as Parylenes, have been considerably adopted by the scientific community for several applications, ranging from simple passive coatings to active device components. Here, we explore the thermal, structural, and electrical properties of Parylene C, and further present a variety of electronic devices featuring this polymer: transistors, capacitors, and digital microfluidic (DMF) devices. We evaluate transistors produced with Parylene C as a dielectric, substrate, and encapsulation layer, either semitransparent or fully transparent. Such transistors exhibit steep transfer curves and subthreshold slopes of 0.26 V/dec, negligible gate leak currents, and fair mobilities. Furthermore, we characterize MIM (metal–insulator–metal) structures with Parylene C as a dielectric and demonstrate the functionality of the polymer deposited in single and double layers under temperature and AC signal stimuli, mimicking the DMF stimuli. Applying temperature generally leads to a decrease in the capacitance of the dielectric layer, whereas applying an AC signal leads to an increase in said capacitance for double-layered Parylene C only. By applying the two stimuli, the capacitance seems to suffer from a balanced influence of both the separated stimuli. Lastly, we demonstrate that DMF devices with double-layered Parylene C allow for faster droplet motion and enable long nucleic acid amplification reactions. publishersversion published

Type-1 diabetes is one of the most prevalent metabolic disorders worldwide. It results in a significant lack of insulin production by the pancreas and the ensuing hyperglycemia, which needs to be regulated through a tailored administration of insulin throughout the day. Recent studies have shown great advancements in developing an implantable artificial pancreas. However, some improvements are still required, including the optimal biomaterials and technologies to produce the implantable insulin reservoir. Here, we discuss the employment of two types of cyclic olefin copolymers (Topas 5013L-10 and Topas 8007S-04) for an insulin reservoir fabrication. After a preliminary thermomechanical analysis, Topas 8007S-04 was selected as the best material to fabricate a 3D-printed insulin reservoir due to its higher strength and lower glass transition temperature (Tg). Fiber deposition modeling was used to manufacture a reservoir-like structure, which was employed to assess the ability of the material to prevent insulin aggregation. Although the surface texture presents a localized roughness, the ultraviolet analysis did not detect any significant insulin aggregation over a timeframe of 14 days. These interesting results make Topas 8007S-04 cyclic olefin copolymer a potential candidate biomaterial for fabricating structural components in an implantable artificial pancreas.

A computational methodology based on supervised machine learning (ML) is described for characterizing and designing anisotropic refractory composite alloys with desired thermal conductivities (TCs). The structural design variables are parameters of our fast computational microstructure generator, which were linked to the physical properties. Based on the Sobol sequence, a sufficiently large dataset of artificial microstructures with a fixed volume fraction (VF) was created. The TCs were calculated using our previously developed fast Fourier transform (FFT) homogenization approach. The resulting dataset was used to train our optimal autoencoder, establishing the intricate links between the material’s structure and properties. Specifically, the trained ML model’s inverse design of tungsten-30% (VF) copper with desired TCs was investigated. According to our case studies, our computational model accurately predicts TCs based on two perpendicular cut-section images of the experimental microstructures. The approach can be expanded to the robust inverse design of other material systems based on the target TCs.

Lithium-ion batteries are known for their high efficiency for storing electrical energy, especially for hybrid vehicles. In this research, the development of mixture composites in the cathode electrode of LIBs has been discussed and designed based on ternary solid solutions. We have given a novel synthesis and method preparation of cathode electrode materials to reduce costs while increasing the efficiency and simultaneity for the future of these technologies. The major problem in the LIBs is related to LiCoO2 as a popular cathode material that, although it has a high efficiency, is expensive and very toxic. Therefore, the usage of a lower weight of cobalt compared to the LiCoO2 cathode material is economically advantageous for this research. Several samples of the (1-x-y) LiCo1/3Ti1/3Fe1/3PO4 xLi2MnPO4 and yLiFePO4 system were synthesized via sol–gel experiments. Various stoichiometric amounts of the LiNO3, Li2MnPO4, Mn (Ac)2. 4H2O, Co (Ac)2.4H2O, Ti(NO3)2.6H2O and LiFePO4 have been used for several compositions of chrome, manganese, cobalt and titanium in 28 samples of (1-x-y) LiCo1/3Ti1/3Fe1/3PO4. By using thermal characterization, five samples have been selected due to their conditions in viewpoints of capacity and cyclability as well as activation energy, which is one of the major factors. These composites exhibited fairly consistent charge/discharge curves during the electrochemical testing. From the viewpoint of the physical and chemical properties, among these samples, the Li1.501Co0.389Ti0.055Fe0.055Mn0.501PO4 structure has a high efficiency compared to other compositions.

The manufacturing technology of historical mortars from the Roman to Medieval period apparently has not undergone evolutions. As reported in the literature, a quality decrease in the raw material occurred after the fall of the Roman Empire. During the Roman Age, the mortars presented the requirements of long durability due to hydraulic characteristics, and in later times, the production has only partially maintained the ancient requirements. To focus on the different production technologies between Roman and Medieval mortar, this research presents the case study of San Saturnino Basilica (Italy), where an archaeological mortar stratigraphy from Roman to Middle Ages is well preserved. An archaeometric characterization was performed to compare the mortars of the Roman period with the mortars of the Medieval period collected from the case-study monument. This comparison was carried out by measuring some physical-mechanical, mineralogical, petrographic and thermal features that give more information about the durability and resistance to mechanical solicitations and weathering. After the characterizations, contrary to what is reported in the bibliography, a better quality of Medieval materials than Roman ones is pointed out. This has been highlighted by higher hydraulicity, mechanical performance, and a more appropriated particle-size distribution of aggregates.

Maintenance of adequate thermal properties is critical for correct operation of a gas foil bearing. In this work, the authors present the results of the experimentally conducted thermal characterization of a prototype installation of the bearing. A novel method of temperature identification, based on integrated thermocouples readings, has been employed to determine the thermal properties of the specialized sensing top foil mounted in the tested bearing. Two measurement campaigns have been subsequently completed, applying freely-suspended and two-node support configurations, to gather complementary knowledge regarding the bearing’s operation. Apart from the rotational speed and temperature field measurements, the authors have also studied the friction torque and the shaft’s journal trajectories based on its radial displacements. The temporal courses for the above-mentioned quantities have enabled inference on the effects present during run-up, run-out and stable state operation at a constant speed. As confirmed, the applied distribution of the integrated sensors allows for temperature readings on the entire outer surface of the foil, and therefore, provides useful data for the bearing characterization. The work is concluded with presentation of the recommended directions regarding future improvements of the proposed measurement technique and more comprehensive study of the bearing’s characteristics.

International audience; Polymerization kinetics as well as thermal properties of acrylic copolymers containing Isobornylacrylate- (IBOA) and2-Ethylhexylacrylate- (2-EHA) units were investigated. Poly(IBOA-co-2-EHA) samples were synthesized via free radicalphotopolymerization/crosslinking reactions of IBOA and 2-EHA, in the presence of 1,6-hexanedioldiacrylate (HDDA) ascrosslinking agent, to obtain chemically crosslinked polymer networks. High conversion rates of the acrylic double bondsof the monomers were obtained from investigation of the polymerization kinetics by infrared spectroscopy. Analysis of thethermal properties using differential scanning calorimetry revealed the appearance of a single glass transition of Poly(IBOAco-2-EHA) over a large range of temperatures comprised between 208 and 321 K, depending on monomer composition. Theevolution of the glass transition temperature was rationalized by applying the Fox, Gordon Taylor, and Brekner-Schneider-Cantow models, revealing presumably the existence of hydrogen bonding interaction involving the carbonyl groups of theacrylates. Several degradation processes were observed by thermogravimetrical analysis, especially that of the isobornylenegroup at low temperature followed by the degradation of the carbon backbone at higher temperatures. Increasing IBOA contentleads to a higher thermal stability of Poly(IBOA-co-2-EHA). Each degradation step could be characterized separatelyexhibiting activation energies which strongly depend on the degradation time of each step.

The recovery and storage of process heat in industrial applications are some of the key factors to improve the sustainability and reliability of high temperature applications. In this sense, one of the main drawbacks is focused on the selection of proper thermal energy storage (TES) materials. This paper performs a full characterization of four phase change storage materials (PCM), KOH, LiOH, NaNO3 and KNO3, which are proposed for storage applications between 270 and 500 °C, according to the results obtained through differential scanning calorimeter and thermogravimetric analysis. One of the main innovations includes the corrosive evaluation of these materials in a promising alumina forming alloy (OC4), close to their corresponding phase change temperature during 500 h. The physicochemical properties obtained confirm the optimal use of NaNO3 and KNO3 and recommend the use, with caution, of KOH, due to its higher corrosive potential. FeCr2O4, NiCr2O4 and FeAl2O4 were the main protective spinels formed in the alloy surface, however, the cross-section study in the alloy immersed in KOH, revealed a non-uniform behavior, presenting some cracks and spallation in the surface. On the other hand, the proposal of LiOH was disregarded since it presents a narrow operation temperature range between melting and solidification point. his research was funded by [Diputación de Guipúzcoa] grant number [1.0420.200.781.00.04.2021] and Ramon y Cajal program [RyC 2020-28787-I].

Controlling thermal energy transfer at the nanoscale and thermal properties has become critically important in many applications since it often limits device performance. In this study, the effects on thermal conductivity arising from the nanoscale structure of free-standing nanocrystalline silicon films and the increasing surface-to-volume ratio when fabricated into suspended optomechanical nanobeams are studied. Thermal transport and elucidate the relative impact of different grain size distributions and geometrical dimensions on thermal conductivity are characterized. A micro time-domain thermoreflectance method to study free-standing nanocrystalline silicon films and find a drastic reduction in the thermal conductivity, down to values below 10 W m–1 K–1 is used, with a stronger decrease for smaller grains. In optomechanical nanostructures, this effect is smaller than in membranes due to the competition of surface scattering in decreasing thermal conductivity. Finally, a novel versatile contactless characterization technique that can be adapted to any structure supporting a thermally shifted optical resonance is introduced. The thermal conductivity data agrees quantitatively with the thermoreflectance measurements. This study opens the way to a more generalized thermal characterization of optomechanical cavities and to create hot-spots with engineered shapes at the desired position in the structures as a means to study thermal transport in coupled photon-phonon structures., This work was supported by the European Commission FET Open project PHENOMEN (G.A. Nr. 713450). ICN2 was supported by the S. Ochoa program from the Spanish Research Agency (AEI, grant no. SEV-2017-0706) and by the CERCA Programme / Generalitat de Catalunya. ICN2 authors acknowledge the support from the Spanish MICINN project SIP (PGC2018-101743-B-I00). D.N.U. and M.F.C. acknowledge the support of a Ramón y Cajal postdoctoral fellowship (RYC-2014-15392) and a Severo Ochoa studentship, respectively. E.C.A. acknowledges financial support from the EU FET Open Project NANOPOLY. (GA 829061). A.M. acknowledges support from Ministerio de Ciencia, Innovación y Universidades (grant PGC2018-094490-B, PRX18/00126) and Generalitat Valenciana (grants PROMETEO/2019/123, and IDIFEDER/2018/033).

Two important biophysical properties, the thermal and UV-Vis screening capacity, of isolated tomato fruit cuticle membranes (CM) have been studied by differential scanning calorimetry (DSC) and UV-Vis spectrometry, respectively. A first order melting, corresponding to waxes, and a second order glass transition (Tg) thermal events have been observed. The glass transition was less defined and displaced toward higher temperatures along the fruit ripening. In immature and mature green fruits, the CM was always in the viscous and more fluid state but, in ripe fruits, daily and seasonal temperature fluctuations may cause the transition between the glassy and viscous states altering the mass transfer between the epidermal plant cells and the environment. CM dewaxing reduced the Tg value, as derived from the role of waxes as fillers. Tg reduction was more intense after polysaccharide removal due to their highly interwoven distribution within the cutin matrix that restricts the chain mobility. Such effect was amplified by the presence of phenolic compounds in ripe cuticle membranes. The structural rigidity induced by phenolics in tomato CMs was directly reflected in their mechanical elastic modulus. The heat capacity (Cprev) of cuticle membranes was found to depend on the developmental stage of the fruits and was higher in immature and green stages. The average Cprev value was above the one of air, which confers heat regulation capacity to CM. Cuticle membranes screened the UV-B light by 99% irrespectively the developmental stage of the fruit. As intra and epicuticular waxes contributed very little to the UV screening, this protection capacity is attributed to the absorption by cinnamic acid derivatives. However, the blocking capacity toward UV-A is mainly due to the CM thickness increment during growth and to the absorption by flavone chalconaringenin accumulated during ripening. The build-up of phenolic compounds was found to be an efficient mechanism to regulate both the thermal and UV screening properties of cuticle membranes., Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación RTI2018-094277- B/AEI/10.13039/501100011033 (co-financed by the European Regional Development Fund, ERDF), Ministerio de Ciencia, Innovación y Universidades” RYC2018-025079-I/AEI/10.13039/501100011033 (co-financed by the European Social Fund, ESF)., Spanish Research Council (CSIC) PIE project 202040E003, MINECO FPU grant (FPU17/01771).

Thermal transient measurement based on source-drain voltage is a standard method to characterize thermal properties of silicon semiconductors but is doubtful to be directly applied to silicon carbide (SiC) devices. To evaluate its feasibility and limitations, this paper conducts a comprehensive investigation into its accuracy, resolution, and stability towards yielding the structure information of SiC MOSFET using the source-drain voltage as the temperature sensitive electrical parameter. The whole characterization process involves two main procedures and associated key testing parameters, such as gate voltages, sensing and heating currents, etc. Their impacts on both the static and dynamic performances are also investigated with the aim of providing a guideline for conducting a reproducible thermal transient measurement for SiC MOSFETs.

This thesis is dedicated to mainly two aspects of heat transport in current research materials. The first aspect is conductive heat transport which, in the investigated non-metals, mostly takes place through vibrations. The second aspect is radiative heat transport which is of particular interest at high temperatures or special applications like passive radiative cooling. First, the photoacoustic technique was theoretically optimized and verified experimentally for the cross-plane conductive thermal characterization of polymeric thin films. With this measurement method, a temperature oscillation is optically excited, which can be measured with a microphone utilizing a resulting pressure oscillation. Depending on the sample's thermal properties, the pressure signal contains information about the surface temperature, which has a characteristic phase shift and amplitude relative to the excitation. Non-linear data analysis can, therefore, be used to determine the properties of the sample by fitting the measurement data to an appropriate multi-layer model. The optimized measurement setup could subsequently be used for the thermal characterization of current research materials in addition to the general proof of applicability. The first systems were P3HT thin films with different molecular weights, prepared from three different solvents, where possible relations between the microstructural optoelectronic properties extracted from deconvolution of absorption spectra and the thermal conductivity were explored. A variation of the optoelectronic properties, mainly regarding molecular weight, was apparent, while no direct influence of the solvent was discernible. In contrast, the thermal conductivities of all examined films demonstrated an insignificant variability. We, therefore, concluded that mainly the amorphous phase determines the thermal transport properties in these semi-crystalline thin films, as these represent a bottleneck for thermal transport. The second systems were fully amorphous ampholytic polymers that exhibited different donor and acceptor groups to form hydrogen bonds. In addition to measurements depending on the humidity and/or water absorption of the polymers, a correlation between the strength of the hydrogen bonds and the thermal conductivity was observed. The strength of the hydrogen bonds was determined by deconvolution of the characteristic carbonyl peak of the IR absorption. A direct correlation between the hydrogen bond strength and the thermal conductivity was observed for the thin films investigated. Thirdly, anisotropic hybrid Bragg stacks of highly ordered fluorohectorite clay layers that alternate with one or two poly(ethylene glycol) layers were explored. For in-plane thermal characterization, lock-in thermography was used to investigate the anisotropy. The mechanical properties were examined using Brillouin light spectroscopy, indicating an almost ideal reinforcement of the hybrid material and exceptionally high Young's moduli. Furthermore, 2D hybrid perovskites were studied compared to the widely used 3D methylammonium lead iodide. The influence of the organic cations on the thermal and electronic properties was investigated using light flash analysis, first-principles and molecular dynamics calculations, ultraviolet photoelectron spectroscopy and Raman measurements. As a result, an atomistic understanding of the effects of dimensional reduction on properties relevant to electronic and thermal transport was developed. While conduction is the dominant transport mechanism in the materials outlined above, radiative transport is the second subject to be investigated. Particulate silica materials are an exciting and at ambient thermally highly insulating material class that was investigated up to 925 °C by light flash analysis. Performing multibody optical simulations and a newly developed model, a transition of the main transport channel from conduction at ambient to radiation at high temperatures was unraveled. Therefore, the materials partially lose their extraordinary insulating properties at high temperatures. The final subject area, passive cooling, is a unique application of radiative heat transport. Although thermal radiation is relatively weak at ambient temperatures, outer space can be used as an ultimate heat sink when carefully designing the emitter material to take advantage of the atmospheric transparency window. First, an approach was developed to determine the optimum emitter thickness to maximize the cooling power at ambient conditions or reach the lowest equilibrium temperature. Furthermore, an in-house setup was designed, which allows reproducible cooling power measurements and the variation of several environmental parameters in contrast to rooftop measurements. In summary, the conductive heat transport in thin films and free-standing samples was investigated in addition to the methodological development. Various structure-property relationships were elucidated, which improved the understanding of thermal transport on small length scales and provides guidance for future material development. Furthermore, through the analysis of radiative heat transport, it could be shown that particulate silica materials, which are highly insulating at room temperature, lose part of their insulating properties at high temperatures. Finally, in the field of passive radiative cooling, it was possible to show how the emitter thickness can be optimized, and a highly reproducible and variable in-house measurement setup was developed.

Current optical communication schema are based on TDMA. New schema have been proposed that are based on WDM. A WDM based scheme needs all lasers to be stable at a fixed wavelength. The wavelength of a laser can be modified by temperature changes. In this work, a typical laser used for optical communications is characterized. A thermal-electrical equivalent model is proposed to model the laser. The necessary experiments have been performed to characterize the laser and extract the model parameters. With the model completed, a PI control scheme has been implemented. This implemented control stabilizes the laser to a certain degree but the fabrication and the layout of the packaging prevent a feedback control to have a high performance. Then, a feed-forward control based on measuring the air temperature is implemented. This feed-forward control improves the stability of the laser in front of temperature changes to a satisfactory degree.

The paper aims to compare different methods able to estimate the specific loss power (SLP) generated by three different types of magnetic nanoparticles, MNPs, dispersed in a suspension fluid, e.g., octane or water. The nanoparticles were characterized morphologically in terms of shape and size, chemically for composition and their physical properties like magnetization and SLP were studied. We evidenced the differences in SLP evaluation due to the applied method, particularly in the presence of thermally induced phenomena such as aggregation or precipitation of MNPs that can affect the heating curve of the samples. Then, the SLP determination methods less sensible to this phenomenon appear to be the ones that use the initial slope when the sample is in quasi-adiabatic condition. Finally, we propose a comparison of those methods based on the pros and cons of their use for the SLP determination of magnetic nanofluids. In particular, the analysis of the behavior of the heating curve is useful to evaluate the useful amplitude of the interval analysis for the initial slope methods.

Cold climate regions have great potential for wind power generation. The available wind energy in these regions is about 10% higher than in other regions due to higher wind speeds and increased air density. However, these regions usually have favorable icing conditions that lead to ice accumulation on the wind turbine blades, which in turn increases the weight of the blades and disrupts local airflow, resulting in a reduction in wind turbine performance. Considering this problem, plasma actuators have been proposed as devices for simultaneous flow control and deicing. These devices transfer momentum to the local airflow, improving the aerodynamic performances of the turbine blades while producing significant thermal effects that can be used to prevent ice formation. Considering the potential application of plasma actuators for simultaneous flow control and deicing, it is very important to investigate the thermal effects induced by these devices. However, due to the significant electromagnetic interference generated by the operation of these devices, there is a lack of experimental techniques that can be used to analyze them. In the current work, a background-oriented Schlieren system was developed and is presented as a new experimental technique for the thermal characterization of the plasma-induced flow. For the first time, the induced flow temperatures are characterized for plasma actuators with different dielectric materials and different dielectric thicknesses. The results demonstrate that, due to the plasma discharge, the temperature of the plasma-induced flow increases with the increase of the applied voltage and may achieve temperatures five times higher than the room temperature, which proves the potential of plasma actuators for deicing applications. The results are presented and discussed with respect to the potential application of plasma actuators for simultaneous flow control and deicing of wind turbine blades.

In this paper, the development of a copper–chrome-based glass microheater and its integration into a Polymethylmethacrylate (PMMA) microfluidic system are presented. The process highlights the importance of an appropriate characterization, taking advantage of computer-simulated physical methods in the heat transfer process. The presented system architecture allows the integration for the development of a thermal flow sensor, in which the fluid flows through a 1 mm width × 1 mm length microchannel across a 5 mm width × 13 mm length heating surface. Using an electrothermal analysis, based on a simulation and design process, the surface heating behavior curve was analyzed to choose a heating reference point, primarily used to control the temperature point within the fluidic microsystem. The heater was characterized using the theory of electrical instrumentation, with a 7.22% error for the heating characterization and a 5.42% error for the power consumption, measured at 0.69 W at a temperature of 70 °C. Further tests, at a temperature of 115 °C, were used to observe the effects of the heat transfer through convection on the fluid and the heater surface for different flow rates, which can be used for the development of thermal flowmeters using the configuration presented in this work.

The drying of fruit juices has advantages such as easy handling of powders, reduction in volume, and preservation of the characteristics of the fruit. Thus, in this work, the effect of the spray drying conditions of strawberry juice (SJ) with maltodextrin (MX) as a carrying agent on the microencapsulation of bioactive compounds and physicochemical properties was studied. The content of phenolic compounds and antioxidant activity showed higher values at low concentrations of MX, while the effect of drying temperature was negligible. The thermal characterization showed that the low molecular weight sugars in the juice decreased the glass transition temperature (Tg). The morphological analysis by scanning electron microscopy (SEM) indicated that at low concentrations of MX, the particles agglomerated, while at intermediate and high concentrations, the particles were observed as well separated. Through microstructural analysis by X-ray diffraction (XRD), the presence of amorphous state was confirmed in all the samples, which is beneficial for preventing chemical and biochemical reactions, and promoting the conservation of the microencapsulated bioactive compounds.

In the framework of ISOL (isotope separation on-line) facilities, porous carbides are among the most employed target materials for the production of radioactive ion beams for research. As foreseen by the ISOL technique, a production target is impinged by an energetic particle beam, inducing nuclear reactions from such an interaction. The resulting radionuclides are subsequently released, thanks to the high target working temperature (1600–2000 °C); ionized; and extracted into a beam. Since the target microstructure and porosity play a fundamental role in the radionuclide release efficiency, custom-made target materials are often specifically produced, resulting in unknown thermal and structural properties. Considering that such targets might undergo intense thermal stresses during operation, a thermal and structural characterization is necessary to avoid target failure under irradiation. In the presented work, a custom-made porous titanium carbide that was specifically designed for application as an ISOL target was produced and characterized. The thermal characterization was focused on the evaluation of the material emissivity and thermal conductivity in the 600–1400 °C temperature range. For the estimation of a reference material tensile stress limit, the virtual thermoelastic parameter approach was adopted. In particular, for the aforementioned temperature range, an emissivity between 0.7 and 0.8 was measured, whereas a thermal conductivity between 8 and 10 W/mK was estimated.

International audience; Thermal characterization of GaN-based components is an important and challenging issue that requires the measurement of the self-heating temperature of the channel, the metal contact surface and the substrate with high accuracy. This paper points out that all these thermal parameters can be measured by combining confocal Raman spectroscopy and micro-Raman thermometers. To prove these assertions, thermal resistance and Thermal Boundary Resistance (TBR) were accurately estimated experimentally. In addition, temperature measurements with TiO2 and CeO2 micro-Raman thermometers were carried out to determine which is more accurate and reliable in measuring the surface self-heating temperature of these components.

Un diagrama de estado es una herramienta útil para visualizar los límites de estabilidad de un material sometido a diferentes condiciones. En este trabajo, se informa el diagrama de estado de equilibrio para la estabilidad de la lactosa beta anhidra pura (Lβ). Para ello, se construyeron isotermas de adsorción a tres temperaturas de almacenamiento (15, 25 y 35 ° C) en un amplio rango de actividad del agua (0,07-0,972). Los polvos obtenidos se caracterizaron mediante espectroscopía Raman, difracción de rayos X (XRD), microscopía electrónica de barrido (SEM) y calorimetría diferencial de barrido modulada (MDSC). Los resultados mostraron una alta estabilidad de Lβ a las temperaturas de almacenamiento, lo que indica una adsorción similar al contenido de monocapa. Por el contrario, el proceso de mutarrotación se desencadenó por la adsorción de agua más allá del contenido de monocapa. En estas condiciones, se observó la presencia de alfa lactosa (Lα). Además, la Tg de Lβ se determinó en el intervalo de -15 a -1,4 ° C en las condiciones de almacenamiento. El presente trabajo contribuye al estudio de la estabilidad de Lβ para establecer su aplicación tecnológica como agente portador o en la microencapsulación de principios activos. A state diagram is a useful tool to visualize the stability limits of a material subjected to different conditions. In this work, the equilibrium state diagram for pure anhydrous beta lactose (Lβ) stability is reported. For this, adsorption isotherms were built at three storage temperatures (15, 25 and 35 ° C) in a wide range of water activity (0.07-0.972). The powders obtained were characterized by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and modulated differential scanning calorimetry (MDSC). The results showed a high stability of Lβ at the storage temperatures, indicating an adsorption similar to the monolayer content. Conversely, the mutarotation process was triggered by the adsorption of water beyond the monolayer content. Under these conditions, the presence of alpha lactose (Lα) was observed. Furthermore, the Tg of the Lβ was determined in the range of -15 to -1.4 °C at the storage conditions. The present work contributes to the study of the stability of Lβ to establish its technological application as a carrier agent or in the microencapsulation of active ingredients. Administradores Investigadores Estudiantes

In Europe, the building sector contributes fort more than one third of greenhouse gas emissions, mainly due to their heating and cooling needs. The last decades have seen the rise of new facade technologies with complex thermal behaviour. Their goal is to make the indoor environment comfortable while minimizing the energy needs of buildings. The thermal characterization of this new kind of facades is therefore crucial to guarantee their performance.To do so, a new "test cell" facility was used. Test cells are facilities typically used to perform experiments under real weather conditions with a wide variety of facades. The objective of this PhD thesis is to develop a methodology for the thermal characterization of facades, both at the component and at the test cell scales. At the component scale, the study focused on a highly insulated opaque façade. Its thermal characteristics were estimated using intrusive temperature measurements by inverse method. The results were compared to the standard non-intrusive method, known as the average method. The intrusive method was able to estimate its capacity in addition to good accuracy on the thermal resistance estimation. At the test cell scale, an opaque wall and a glazed facade were studied. A coupled heat and airflow model was developed. It helped the conception of a methodology that estimates the thermal resistances of a façade and the walls of the test cell, despite the high correlation of these parameters. This study allowed to have a more accurate overview of the technical potential of this installation and it led to the definition of guidelines for future experimental works., En Europe, le secteur du bâtiment représente plus d’un tiers des émissions de gaz à effet de serre, principalement dues à leurs besoins de chauffage et de climatisation. Ces dernières décennies ont vu apparaître de nouvelles technologies de façades aux comportements thermiques complexes. Leur but est de rendre l’environnement intérieur confortable tout en limitant les besoins énergétiques des bâtiments. La caractérisation thermique de ces façades est donc essentielle afin de garantir leur performance. À cette fin, une nouvelle installation de type « cellule-test » a été utilisée. Cet équipement expérimental permet de tester des façades en conditions climatiques réelles, tout en disposant d’un volume intérieur contrôlé en température et dont les flux sont maîtrisés. L’objectif de la thèse est de mettre au point des méthodologies de caractérisation thermique des façades, à l’échelle du composant et à l’échelle de la cellule-test. À l’échelle du composant, l’étude a porté sur une façade opaque fortement isolée. Ses caractéristiques thermiques ont été estimées à l’aide des mesures de températures intrusives par méthode inverse. Les résultats ont été comparés à une méthode non-intrusive : la méthode normalisée de la moyenne. En plus d’une bonne précision sur l’estimation de la résistance thermique de la paroi, la méthode intrusive a permis d’en estimer la capacité. À l’échelle de la cellule-test, des façades opaque et vitrée ont été étudiées. En complément des mesures expérimentales, un modèle thermo-aéraulique a été développé. Il a aidé à la construction d’une méthodologie qui estime les résistances thermiques d’une façade et des parois de la cellule-test, malgré la forte corrélation de ces paramètres. Cette étude a abouti à la formulation de préconisations pour la réalisation de futurs essais expérimentaux.

A new method for estimating the thermal properties of composite materials is proposed. It uses a previously developed thermal characterization method that is based on Karhunen–Loève decomposition (KLD) techniques in association with infrared thermography experiments or any other kind of experimental device providing dense data in spatial coordinates. The novelty of this work lies in the introduction of two techniques based on two phase-wise defined test functions that extend the previously developed method to cases where the morphology of the composite material is not straightforward. Thanks to the orthogonal properties of KLD, only a few eigenelements are needed for an accurate estimation, which allows for a significant amplification of the signal/noise ratios. Furthermore, the proposed methods represent an attractive combination of parsimony and robustness to noise thanks to spatially uncorrelated noise being entirely reported on states. The effectiveness and accuracy of both techniques are proven with numerical tests.

Climate change (CC) is predominantly connected to greenhouse gas (GHG) emissions from the construction sector. It is clear how it is necessary to rethink construction materials in order to reduce GHG emissions. Among the various strategies proposed, recent research has investigated the potential of smart materials. This study in particular aims to develop an innovative building component that combines high energy performance with reduced thickness and weight. For this reason, the potential of Phase Change Materials (PCM) in cement-based mixes is investigated, comparing the performance of a traditional mix with two innovative mixes made with the addition of 3% and 7% PCM. This work characterizes the new material, analyzing its mechanical and thermal performance, highlighting how the mix strength decreases as the PCM ratio increases, however, both mixes may be considered suitable for masonry structures and may be classified as M5 and M15. Furthermore, from the analysis of the thermal performance, it emerges that the mix presents good behavior in terms of insulating properties.

Cellular solids and porous metals have become some of the most promising lightweight multifunctional materials due to their superior combination of advanced properties mainly derived from their base material and cellular structure. They are used in a wide range of commercial, biomedical, industrial, and military applications. In contrast to other cellular materials, cellular metals are non-flammable, recyclable, extremely tough, and chemically stable and are excellent energy absorbers. The manuscripts of this Special Issue provide a representative insight into the recent developments in this field, covering topics related to manufacturing, characterization, properties, specific challenges in transportation, and the description of structural features. For example, a presented strategy for the strengthening of Al-alloy foams is the addition of alloying elements (e.g., magnesium) into the metal bulk matrix to promote the formation of intermetallics (e.g., precipitation hardening). The incorporation of micro-sized and nanosized reinforcement elements (e.g., carbon nanotubes and graphene oxide) into the metal bulk matrix to enhance the performance of the ductile metal is presented. New bioinspired cellular materials, such as nanocomposite foams, lattice materials, and hybrid foams and structures are also discussed (e.g., filled hollow structures, metalpolymer hybrid cellular structures). published

National audience; During the characterization, the procedure required to imagine an experiment that can be simulated by a model simple enough to guarantee a quick construction of the solution. The Symbolic Monte-Carlo method appears to be an interesting method for dealing with multi-physical 3D problems, in particular due to its insensitivity to geometrical complexity, the transfer function it allows to produce and its capacity to quickly provide a solution for different values of a given thermophysical parameter. An implementation of the Monte-Carlo Symbolic method is described and studied within the framework of the resolution of a thermal properties identification problem consisting in characterizing the thermal diffusivity by the flash method.; Lors de la procédure de caractérisation, l’inverseur est contraint d’imaginer une expérience pouvant être simulée par un modèle suffisamment simple pour garantir une construction rapide de la solution. La méthode de Monte-Carlo Symbolique apparaît comme une méthode intéressante pour traiter les problèmes 3D multi-physiques notamment grâce à son insensibilité a` la complexité géométrique, la fonction de transfert qu’elle permet de produire et sa capacité à fournir rapidement une solution pour différentes valeurs d’un paramètre thermophysique donné. Une mise en œuvre de la méthode de Monte-Carlo Symbolique est décrite et étudiée dans le cadre de la résolution d’un problème d’estimation de propriétés consistant à caractériser la diffusivité thermique par la méthode flash.

In the facilities for the production of Radioactive Ion Beams (RIBs) according to the Isotope Separation On-Line (ISOL) technique, a production target is typically impinged by a high-power primary beam, generating radioactive isotopes for basic research and technological applications. With the aim to guarantee an efficient extraction of the aforementioned isotopes, the production target must work in a high vacuum environment, at temperatures that are usually between 1600 °C and 2200 °C. Its main components are often characterized by intense temperature gradients and consequently by severe thermal stresses. Carbides are widely used for target manufacturing, and in this work a specific method for their thermal and mechanical characterization is presented and discussed. It is based on the comparison between experimental measurements and numerical simulations, with the introduction of the novel Virtual Thermoelastic Parameters approach for the structural verification procedure. High-performance silicon carbides (SiC) are taken as a reference to describe the method. Measured emissivity and thermal conductivity data are presented and discussed, together with the experimental estimation of material limitations for both temperature and stress fields. The aforementioned results can be promptly used for the design process of high-power ISOL targets.

Heat dissipation and thermal management are central challenges in various areas of science and technology and are critical issues for the majority of nanoelectronic devices. In this review, we focus on experimental advances in thermal characterization and phonon engineering that have drastically increased the understanding of heat transport and demonstrated efficient ways to control heat propagation in nanomaterials. We summarize the latest device-relevant methodologies of phonon engineering in semiconductor nanostructures and 2D materials, including graphene and transition metal dichalcogenides. Then, we review recent advances in thermal characterization techniques, and discuss their main challenges and limitations., ICN2 is supported by the Severo Ochoa program, the Spanish Research Agency (AEI, grant no. SEV-2017-0706) and the CERCA Programme/Generalitat de Catalunya. Authors acknowledge support from Spanish MICINN project SIP (PGC2018-101743-B-I00), and the EU project NANOPOLY (GA 289061).

With growing environmental concerns over synthetic polymers, natural polymeric materials, such as hemicellulose, are considered a good sustainable alternative. Curaua fibers could be an excellent source of biopolymer as they have a relatively high hemicellulose content (15 wt%) and only a small amount of lignin (7 wt%). In this work, hemicellulose was extracted by an alkaline medium using KOH and the influence of the alkali concentration, temperature, and time was studied. A hemicellulose film was produced by water casting and its mechanical, thermal, and morphological properties were characterized. The results show that the best method, which resulted in the highest hemicellulose yield and lowest contamination from lignin, was using 10% (w/v) KOH concentration, 25 °C, and time of 3 h. The hemicellulose film exhibited better thermal stability and elongation at break than other polymeric films. It also exhibited lower rigidity and higher flexibility than other biodegradable polymers, including polylactic acid (PLA) and polyhydroxybutyrate (PHB).

Positively charged NCs of TZP (0.1%, w/v) for ocular use were prepared by the antisolvent precipitation method. TZP is a novel 5-Hydroxymethyl-Oxazolidinone class of antibiotic and is effective against many drug-resistant bacterial infections. Even the phosphate salt of this drug is poorly soluble, therefore the NCs were prepared for its better solubility and ocular availability. P188 was found better stabilizer than PVA for TZP-NCs. Characterization of the NCs including the particle-size, PDI, and ZP by Zeta-sizer, while morphology by SEM indicated that the preparation technique was successful to get the optimal sized (151.6 nm) TZP-NCs with good crystalline morphology. Mannitol (1%, w/v) prevented the crystal growth and provided good stabilization to NC1 during freeze-drying. FTIR spectroscopy confirmed the nano-crystallization did not alter the basic molecular structure of TZP. DSC and XRD studies indicated the reduced crystallinity of TZP-NC1, which potentiated its solubility. An increased solubility of TZP-NC1 (25.9 µgmL−1) as compared to pure TZP (18.4 µgmL−1) in STF with SLS. Addition of stearylamine (0.2%, w/v) and BKC (0.01%, w/v) have provided cationic (+29.4 mV) TZP-NCs. Redispersion of freeze-dried NCs in dextrose (5%, w/v) resulted in a clear transparent aqueous suspension of NC1 with osmolarity (298 mOsm·L−1) and viscosity (21.1 cps at 35 °C). Mannitol (cryoprotectant) during freeze-drying could also provide isotonicity to the nano-suspension at redispersion in dextrose solution. In vitro release in STF with SLS has shown relatively higher (78.8%) release of TZP from NC1 as compared to the conventional TZP-AqS (43.4%) at 12 h. TZP-NC1 was physically and chemically stable at three temperatures for 180 days. The above findings suggested that TZP-NC1 would be a promising alternative for ocular delivery of TZP with relatively improved performance.

Leather tanned with different agents was pyrolyzed in the presence of CoCl2 and MnCl2 catalysts. A bovine leather sample tanned with two inorganic tanning agents (chromium and titanium salts) and two organic tanning agents (glutaraldehyde and methylacrylic resin) has been used in this study. The samples were soaked in solutions of CoCl2 or MnCl2 of known concentration. The influence on decomposition temperature and the resultant pyrolysis compounds has been evaluated by using thermogravimetric analysis (TG/DTG) and flash pyrolysis (Py-GC/MS). A multivariate analysis has been applied to the pyrolysis products obtained confirming the effect of the catalyst treatment on leather, specifically on samples tanned with organic agents. According to the results, CoCi2 (higher Lewis acidity) shows a greater influence than the MnCI2 (lower Lewis acidity). The results indicate that the presence of chlorides affects the nature of the pyrolysis products, increasing the yield of the aromatic compounds in all the samples, thus improving the added-value of the volatiles. These catalysts reduced slightly the decomposition temperature. Co-financial support for this investigation has been provided by IMPIVA, Generalitat Valenciana, and FEDER for research within the field of pyrolysis flash of leather waste.

Datacenters are at the heart of the AI, Industry 4.0 and cloud revolution. A datacenter contains a large number of computing nodes hosted in a large temperature-controlled room. Due to the increasing total power and power density of computing nodes, the overall datacenter compute capacity is often capped by peak power consumption and temperature bottlenecks. To preserve the homogeneous performance assumption between all the nodes, complex cooling solution are required, but they might not be sufficient. In this work, we analysed and characterised the thermal properties of a Tier0 datacenter deploying advanced hybrid cooling technologies: specifically, we studied the spatial and temporal heterogeneity during production and cooling emergency hazards. This paper gives first quantitative evidence of thermal bottlenecks in real-life production workload, showing the presence of significant spatial thermal heterogeneity which could be exploited by thermal-aware job scheduling and datacenter-room run-time workload adaptation and distribution.

The aim of this study was to evaluate the changes in the characteristics of Eucalyptus spp. from Paraíba Valley region, Sao Paulo - Brazil after torrification process. Torrification is a thermochemical process that occurs at temperatures lower than the pyrolysis process as a pretreatment to improve biomass characteristics for use as biofuel energy in power generation. An experimental study was carried out in a batch reactor at three temperatures (240 °C, 260 °C and 280 °C) with residence time of 30 and 60 minutes. At the indicated operating conditions by elemental analysis, higher heating value and thermogravimetric analysis were evaluated. Result showed that there was a reduction in the oxygen/carbon (O/C) and hydrogen/carbon (H/C) ratios, causing an increase in the thermal energy quality of torrified wood, about of 28 % and 47 % at temperatures of 260 °C with residence time of 60 minutes and 280 °C with 30 minutes, respectively. A thermogravimetric analysis showed that at 260 °C the hemicellulose was almost completely degraded leaving the fuel in better conditions for combustion or gasification processes.

Made available in DSpace on 2021-06-25T11:15:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Banana-crop represents an essential segment in Brazil’s socio-economic structure. However, the residues of banana-crop discarded cause problems of contamination in the crop and environment. Waste reuse technologies for the production of new chemical compounds with high conditioning and nutritional potential of soils are emerging as an efficient and economically viable way in terms of production and market value. From this perspective, the banana-crop residues torrefied, containing incorporated fertilizers, appears as an alternative to the reuse of that biomass in the generation of a slow-release biofertilizer. Biochar was produced from banana-crop pseudostem by torrefaction at 240 °C (BF sample). Urea (N), KCl (K), and diammonium phosphate (P) were added to BF, then pelletized to produce the BF-N, BF-K, and BF-P fertilizers. The relative water sorption kinetics by time was evaluated using an exponential method, with a maximum of 10.5% (w/w) sorption for the BF-N sample and a maximum adsorption time (95%) of 22.25h. The swelling of BF in water was evaluated by TMA, with a maximum ε = 22.4%. TG and DTG curves were used to obtain the proximate analysis, the thermal stability of the samples, and the urea content overtime of the BF-N sample in an aqueous medium and soil. FTIR spectra allowed to evaluate the interactions of N, P, and K with BF during the production of BF-N, BF-P, and BF-K. Two models, exponential (EM) and quotient (QM), were proposed and assessed for release kinetic parameters of N, P, and K from BF, BF-N, BF-P, and BF-K fertilizers in water and two kinds of soils under controlled conditions. The kinetics parameters allowed a discussion on the mechanisms of nutrient release in both water and soil, and the adjustment of the kinetic release model showed the potential for application as slow-release fertilizers. São Paulo State University (Unesp) Institute of Chemistry São Paulo State University (Unesp) Institute of Chemistry

As a refractory material, molybdenum is regarded with high interest for high-temperature applications. The concurrent use of powder bed Additive Manufacturing (AM) technology can provide significant design and production advantages. In this work, the Laser Powder Bed Fusion (LPBF) process parameters tuning lead to produce almost fully-dense AM Mo blocks (density of 99.5 ± 0.5%). Fine-tuning of the parameters, also involved the Single Scan Tracks analysis, are aiming at the continuous and homogeneous melt-pools production. High-density Mo specimens have been characterized at room- and high-temperature in terms of thermal and mechanical properties, then compared with conventionally manufactured Mo samples. The thermal diffusivity measurement at room temperature allowed to verify that the thermal conductivity value of AM Mo is approximately half of standard Mo. Stress relieving heat treatment improves the thermal conductivity approximately by 13%. The estimation of emissivity and thermal conductivity carried out in the 600÷1600 °C temperature range led to a similar result. The Vickers microhardness measured on fully dense specimens (212 ± 18 HV0.15) is similar to commercially available Mo. Tensile tests have been performed at both room temperature and 600 °C. The effect of building direction and post-processing machining of AM specimens have been also investigated for tests at room temperature. Although the AM samples exhibited a very similar density to standard Mo, the AM Mo mechanical properties resulted generally lower.

In this paper a new low-cost stretchable coplanar capacitive sensor for liquid level sensing is presented. It has been 3D-printed by employing commercial thermoplastic polyurethane (TPU) and conductive materials and using a fused filament fabrication (FFF) process for monolithic fabrication. The sensor presents high linearity and good repeatability when measuring sunflower oil level. Experiments were performed to analyse the behaviour of the developed sensor when applying bending stimuli, in order to verify its flexibility, and a thermal characterization was performed in the temperature range from 10 °C to 40 °C to evaluate its effect on sunflower oil level measurement. The experimental results showed negligible sensitivity of the sensor to bending stimuli, whereas the thermal characterization produced a model describing the relationship between capacitance, temperature, and oil level, allowing temperature compensation in oil level measurement. The different temperature cycles allowed to quantify the main sources of uncertainty, and their effect on level measurement was evaluated.

In numerical thermal simulation, the inverse problem consists in finding one or more parameters of the discretized heat equation from temperature measurements. This is a complex procedure that often remains limited to simple geometry. The idea is then to use modal-type thermal reduced models, which will considerably reduce the number of unknowns while maintaining satisfactory accuracy over the entire modelled domain. These models will then allow to extend the technique of inverse problems to any type of geometry, whatever its complexity.The objective of this thesis work is to evaluate the efficiency of such a method for an application related to building thermics, in which one seeks to identify the properties of insulating materials (thermal capacity and conductivity).The main work has been the application of this technique for an in situ measurement, using a hot wire probe, which has so far been unsuitable for thermal insulation.A second application of this technique to solve inverse problems by reduced model is the characterization of a bio-sourced material from tomographic surveys at the microscopic scale.For these two applications, the digital developments carried out have allowed the realization of encouraging first experimental trials.; En simulation numérique thermique, le problème inverse consiste à partir de mesures de température, à retrouver un ou plusieurs paramètres de l'équation de la chaleur discrétisée. C'est une procédure complexe qui reste souvent limitée à une géométrie simple. L'idée est alors d'utiliser des modèles réduits thermiques de type modaux, qui vont permettre de diminuer considérablement le nombre d'inconnues tout en maintenant une précision satisfaisante sur l'intégralité du domaine modélisé. Ces modèles vont alors permettre d'étendre la technique des problèmes inverses à tout type de géométrie, quelle que soit sa complexité.L'objectif de ce travail de thèse consiste à évaluer l'efficacité d'une telle méthode pour une application liée à la thermique du bâtiment, dans laquelle on cherche à identifier les propriétés de matériaux isolants (capacité et conductivité thermiques).Le principal travail a été la mise en application de cette technique pour une mesure in situ, via une sonde de type fil chaud, jusqu'ici inadaptée aux isolants thermiques.Une seconde application de cette technique de résolution de problèmes inverses par modèle réduit est la caractérisation d'un matériau bio-sourcé à partir de relevés tomographiques à l'échelle microscopique.Pour ces deux applications, les développements numériques effectués ont permis la réalisation de premiers essais expérimentaux encourageants.

In numerical thermal simulation, the inverse problem consists in finding one or more parameters of the discretized heat equation from temperature measurements. This is a complex procedure that often remains limited to simple geometry. The idea is then to use modal-type thermal reduced models, which will considerably reduce the number of unknowns while maintaining satisfactory accuracy over the entire modelled domain. These models will then allow to extend the technique of inverse problems to any type of geometry, whatever its complexity.The objective of this thesis work is to evaluate the efficiency of such a method for an application related to building thermics, in which one seeks to identify the properties of insulating materials (thermal capacity and conductivity).The main work has been the application of this technique for an in situ measurement, using a hot wire probe, which has so far been unsuitable for thermal insulation.A second application of this technique to solve inverse problems by reduced model is the characterization of a bio-sourced material from tomographic surveys at the microscopic scale.For these two applications, the digital developments carried out have allowed the realization of encouraging first experimental trials.; En simulation numérique thermique, le problème inverse consiste à partir de mesures de température, à retrouver un ou plusieurs paramètres de l'équation de la chaleur discrétisée. C'est une procédure complexe qui reste souvent limitée à une géométrie simple. L'idée est alors d'utiliser des modèles réduits thermiques de type modaux, qui vont permettre de diminuer considérablement le nombre d'inconnues tout en maintenant une précision satisfaisante sur l'intégralité du domaine modélisé. Ces modèles vont alors permettre d'étendre la technique des problèmes inverses à tout type de géométrie, quelle que soit sa complexité.L'objectif de ce travail de thèse consiste à évaluer l'efficacité d'une telle méthode pour une application liée à la thermique du bâtiment, dans laquelle on cherche à identifier les propriétés de matériaux isolants (capacité et conductivité thermiques).Le principal travail a été la mise en application de cette technique pour une mesure in situ, via une sonde de type fil chaud, jusqu'ici inadaptée aux isolants thermiques.Une seconde application de cette technique de résolution de problèmes inverses par modèle réduit est la caractérisation d'un matériau bio-sourcé à partir de relevés tomographiques à l'échelle microscopique.Pour ces deux applications, les développements numériques effectués ont permis la réalisation de premiers essais expérimentaux encourageants.

Thermochemical heat storage is rested on a principle of a reversible chemical reaction : endothermic in one way or exothermic in the other. This type of heat storage based on consecutive hydration and dehydration cycles of hygroscopic salt crystals falls within an approach of reduction of energy consumption of new and existing buildings. Thanks to its high theoretical performance, thermochemical heat storage is tending towards getting ahead of other energy storage systems as sensible or latent storage, especially for long term thermal storage. Nevertheless, the studies carried out in this field show that mass transfers remain low and far from conceivable theoretical values. The cause is linked to the formation of hydrates on the superficial layers of crystals which limit or even prevent any hydration, and therefore any heat transfer. In order to counteract the negative effect of this phenomenon, composites materials composed of a porous matrix with impregnated salts are studied. They should allow avoiding parasitic reactions during the hydration process (exothermic) by physically separating each crystal of reactive salt. In the literature, three salts have been identified as promising for heat storage in a building applications : strontium bromide (SrBr 2 ), magnesium sulfate (MgSO 4 ) and lanthanum chloride (LaCl 3 ). The literature on the latter is limited and results are not converge. In this context, thermal characterization studies by thermogravimetric analysis (ATG-DSC) were carried out in dehydration process on LaCl 3 samples. A method for determining the onset temperature of chemical reactions was developed and used in order to find the equilibrium diagram of this salt. Composite materials were then manufactured by impregnation of salts in a porous ceramic matrix manufactured by 3D printing at the partner laboratory : MATEIS. Finally, an experimental bench test was designed and set up in the laboratory in order to test the performances of LaCl 3 on a larger scale and to compare this salt with the other promising.This thermochemical reactor, reproduced on a laboratory scale, allowed to study mass and heat transfers within reactive salts. The LaCl 3 has been tested for different configurations : in a salt bed and as ceramic composite material. Tests were also carried out on commercial foams of alumina and polyurethane. The cyclability and thermal performance of these composite materials have been evaluated and compared, Le stockage thermochimique repose sur le principe d’une réaction renversable : endothermique dans un sens et exothermique dans l’autre. Ce type de stockage de chaleur basé sur des cycles d’hydratation et de déshydratation de cristaux de sels réactifs, s’inscrit dans un contexte de réduction de la consommation d’énergie des bâtiments et de valorisation des énergies renouvelables. Néanmoins, les études menées dans ce domaine montrent que les transferts de masse restent faibles et loin des valeurs théoriques envisageables. La cause est liée à la formation d'hydrates sur les couches superficielles des cristaux qui limitent voire empêchent toute hydratation, et donc tout transfert de chaleur. Afin de remédier à ce problème d’agglomération, l’utilisation de matrices poreuses a été envisagée. Elles devraient permettre le bon déroulement de la réaction d’hydratation (exothermique) en séparant physiquement chaque cristal de sel réactif. Dans la littérature, trois sels ont été identifiés comme prometteurs pour le stockage de chaleur dans un contexte bâtiment : le bromure de strontium (SrBr 2 ), le sulfate de magnésium (MgSO 4 ) et la chlorure de lanthane (LaCl 3 ). La littérature concernant ce dernier est limitée et les résultats ne convergent pas. Dans ce contexte, des études de caractérisations thermiques par analyse thermogravimétrique (ATG-DSC) ont été réalisées en déshydratation sur des échantillons de LaCl 3 . Une méthode de détermination de la température de déclenchement des réactions chimiques a été mise au point et utilisée afin de tracer le diagramme d’équilibre de ce sel. Des matériaux composites ont ensuite été fabriqués par imprégnation de sels dans une matrice poreuse en céramique fabriquée par impression 3D au laboratoire partenaire : MATEIS. Enfin, un banc expérimental a été conçu et mis en place au laboratoire afin de tester les performances du LaCl3 à plus grande échelle et de les comparer aux autres sels prometteurs. Ce réacteur thermochimique, reproduit à l'échelle du laboratoire a permis d’étudier les transferts de masse et chaleur au sein des sels réactifs. Le LaCl 3 a été testé pour différentes mises en œuvre : en lit de sel et sous forme de matériau composite de céramique. Des essais ont également effectués sur des mousses commerciales d’alumine et de polyuréthane. La cyclabilité et les performances thermiques de ces matériaux composites ont été évaluées et comparées

A thermoplastic starch (TPS) material is developed, based on corn starch plasticized with glycerol and citric acid in a 9:3:1 ratio and further bonded with isinglass and mono- and diglycerides of fatty acids (E471). In TPS, leather fragments, in the amount of 7.5 15 or 22.5 g/100 g of dry matter, were also introduced. The mixture was heated at a maximum temperature of 80 &deg, C, then cast in an open mold to obtain films with thickness in the range 300 &plusmn, 50 microns. The leather fragments used were based on collagen obtained from production waste from shoemaking and tanned with tannins obtained from smoketree (Rhus cotinus), therefore free from chromium. Thermogravimetric (TGA) tests suggested that material degradation started at a temperature around 285 &deg, C, revealing that the presence of leather fragments did not influence the occurrence of this process in TPS. Tensile tests indicated an increase in tensile properties (strength and Young&rsquo, s modulus) with increasing leather content, albeit coupled, especially at 22.5 wt%, with a more pronounced brittle behavior. Leather waste provided a sound interface with the bulk of the composite, as observed under scanning electron microscopy. The production process indicated a very limited degradation of the material after exposure to UV radiation for eight days, as demonstrated by the slight attenuation of amide I (collagen) and polysaccharide FTIR peaks. Reheating at 80 &deg, C resulted in a weight loss not exceeding 3%.

Experimental and numerical techniques for the study of phase change are numerous. The diversity of existing method can be explained by the variety of properties of interest associated to phase change. Amongst them, some techniques aim at establishing the phase diagrams of systems of materials and all present the common characteristic of being time-consuming. In the frame of the study and development of new materials, they appear rather unadapted to the requirements of the industry. A method based on infrared thermography has been developed in order to overcome this limit of standard techniques. It allows for the establishment of phase diagrams in a less than two hours experiment. The proof of the validity of this concept was made on organic systems presenting simple phase diagrams. In this work, its applicability for the determination of phase diagrams of increasing complexity is evaluated. For its optimization, studies are performed in order to assess the influence experimental parameters on the efficiency and quality of results of the method. Finally, its potential applications and limits are investigated.; Les techniques expérimentales et numériques destinées à l’étude du changement de phases sont nombreuses. La diversité des méthodes existantes s’explique par la variété des propriétés d’intérêt associées au changement de phases. On trouve parmi elles des techniques visant à établir le diagramme de phases de systèmes de matériaux. Celles-ci présentent la caractéristique commune d’être chronophage. Dans le cadre de l’étude et développement de nouveaux matériaux, elles apparaissent inadaptées aux exigences de l’industrie. Une méthode basée sur la thermographie infrarouge a été développée afin de pallier cette limite des techniques standards. Elle permet l’établissement d’un diagramme de phases approché en une seule expérience de moins de deux heures. La preuve de la validité de son concept a été faite sur des systèmes organiques présentant des diagrammes de phases simples. Dans ces travaux, son applicabilité est évaluée pour l’établissement de diagrammes de phases de complexité croissante. En vue de son optimisation, des études sont menées visant à mesurer l’influence des conditions opératoires sur son efficacité et la qualité des résultats obtenus. Enfin, ses applications potentielles et ses limites sont investiguées.

[EN] Eco-effcient Wood Plastic Composites (WPCs) have been obtained using poly(hydroxybutyrate-co-hexanoate) (PHBH) as the polymer matrix, and almond shell flour (ASF), a by-product from the agro-food industry, as filler/reinforcement. These WPCs were prepared with different amounts of lignocellulosic fillers (wt %), namely 10, 20 and 30. The mechanical characterization of these WPCs showed an important increase in their stiffness with increasing the wt % ASF content. In addition, lower tensile strength and impact strength were obtained. The field emission scanning electron microscopy (FESEM) study revealed the lack of continuity and poor adhesion among the PHBH-ASF interface. Even with the only addition of 10 wt % ASF, these green composites become highly brittle. Nevertheless, for real applications, the WPC with 30 wt % ASF is the most attracting material since it contributes to lowering the overall cost of the WPC and can be manufactured by injection moulding, but its properties are really compromised due to the lack of compatibility between the hydrophobic PHBH matrix and the hydrophilic lignocellulosic filler. To minimize this phenomenon, 10 and 20 phr (weight parts of OLA-Oligomeric Lactic Acid per one hundred weight parts of PHBH) were added to PHBH/ASF (30 wt % ASF) composites. Differential scanning calorimetry (DSC) suggested poor plasticization effect of OLA on PHBH-ASF composites. Nevertheless, the most important property OLA can provide to PHBH/ASF composites is somewhat compatibilization since some mechanical ductile properties are improved with OLA addition. The study by thermomechanical analysis (TMA), confirmed the increase of the coeffcient of linear thermal expansion (CLTE) with increasing OLA content. The dynamic mechanical characterization (DTMA), revealed higher storage modulus, E¿, with increasing ASF. Moreover, DTMA results confirmed poor plasticization of OLA on PHBH-ASF (30 wt % ASF) composites, but interesting compatibilization effects., This research work was funded by the Spanish Ministry of Science, Innovation, and Universities (MICIU) project number MAT2017-84909-C2-2-R. This work was supported by the POLISABIO program grant number (2019-A02). J. Ivorra-Martinez is the recipient of an FPI grant from Universitat Politècnica de València (PAID-2019). L. Quiles-Carrillo wants to thank GV for his FPI grant (ACIF/2016/182) and MECD for his FPU grant (FPU15/03812). Microscopy services at UPV are acknowledged for their help in collecting and analyzing FESEM images.

Eco-efficient Wood Plastic Composites (WPCs) have been obtained using poly(hydroxybutyrate-co-hexanoate) (PHBH) as the polymer matrix, and almond shell flour (ASF), a by-product from the agro-food industry, as filler/reinforcement. These WPCs were prepared with different amounts of lignocellulosic fillers (wt %), namely 10, 20 and 30. The mechanical characterization of these WPCs showed an important increase in their stiffness with increasing the wt % ASF content. In addition, lower tensile strength and impact strength were obtained. The field emission scanning electron microscopy (FESEM) study revealed the lack of continuity and poor adhesion among the PHBH-ASF interface. Even with the only addition of 10 wt % ASF, these green composites become highly brittle. Nevertheless, for real applications, the WPC with 30 wt % ASF is the most attracting material since it contributes to lowering the overall cost of the WPC and can be manufactured by injection moulding, but its properties are really compromised due to the lack of compatibility between the hydrophobic PHBH matrix and the hydrophilic lignocellulosic filler. To minimize this phenomenon, 10 and 20 phr (weight parts of OLA-Oligomeric Lactic Acid per one hundred weight parts of PHBH) were added to PHBH/ASF (30 wt % ASF) composites. Differential scanning calorimetry (DSC) suggested poor plasticization effect of OLA on PHBH-ASF composites. Nevertheless, the most important property OLA can provide to PHBH/ASF composites is somewhat compatibilization since some mechanical ductile properties are improved with OLA addition. The study by thermomechanical analysis (TMA), confirmed the increase of the coefficient of linear thermal expansion (CLTE) with increasing OLA content. The dynamic mechanical characterization (DTMA), revealed higher storage modulus, E’, with increasing ASF. Moreover, DTMA results confirmed poor plasticization of OLA on PHBH-ASF (30 wt % ASF) composites, but interesting compatibilization effects.

The authors would like to acknowledge to the staff of the Hospital Universitario Clínico San Cecilio, Granada, Spain, for their support and use of the facilities. We also thank the reviewers for their useful and constructive comments and suggestions which have improved this paper., Safe quality control of radiotherapy treatments lies in reliable dosimetric sensors. Currently, ionization chambers and solid-state diodes along with electrometers as readout systems are accomplishing this task. In this work, we present a well-known and low-cost semiconductor sensor, the light-dependent resistor (LDR), as an alternative to the existing sensing devices for dosimetry. To demonstrate this, a complete characterization of the response to radiation of commercial LDRs has been conducted in terms of sensitivity, reproducibility and thermal correction under different bias voltages. Irradiation sessions have been applied under the common conditions in radiotherapy treatments using a hospital linear accelerator. Moreover, the same electrometer used for the ionization chamber has also been successfully used for LDRs. In comparison with the sensitivity achieved for the ionization chamber (0.2 nC/cGy at 400 V bias voltage), higher sensitivities have been measured for the proposed LDRs, ranging from 0.24 to 1.04 nC/cGy at bias voltages from 30 to 150 V, with a reproducibility uncertainty among samples of around 10%. In addition, LDR temperature dependence has been properly modeled using the simple thermistor model so that an easy thermal drift correction of dose measurements can be applied. Therefore, experimental results show that LDRs can be a reliable alternative to dosimetric sensors with the advantages of low size, affordable cost and the fact that it could be adopted with minimal changes in routine dosimetry quality control since the same readout system is fully compatible., Junta de Andalucía B-TIC-468-UGR18 PI-0505-2017, European Union (EU)